1. Field of the Invention
This invention relates to an original pressing device of an image formation apparatus.
2. Description of the Prior Art
In image formation apparatus including printers, facsimiles and electrophotographic copying apparatus, an original to be copied must be uniformly pressed on an original supporting surface irrespective of the thickness of the original in order to ensure that clear images of good quality are obtained. For this reason, the original pressing device according to the prior art is of such a construction as shown in FIG. 1 of the accompanying drawings wherein an elongate arm 4 is associated with a hinge 3 provided on an original supporting surface 2 and the arm 4 is passed through a hole 6 formed in a copying apparatus body 5 so that the hinge 3 is rockable up and down. With such construction, if an original pressing plate 1 is opened and closed by gripping a handle H, even a thick original 7 such as a book or the like can be relatively uniformly brought into contact with the original supporting surface 2. However, the original pressing plate 1 is of a construction in which the hinge 3 and the arm 4 are made integral with each other and this leads to compexity and high cost of the device and sometimes, sliding movement of the hinge 3 and arm 4 has produced noise which has also been offensive to the ear.
FIG. 2 of the accompanying drawings is a side cross-sectional view of another conventional original pressing plate disclosed in U.S. Pat. No. 4,157,222. This original pressing plate 1' comprises a flat core number 8 sandwiched between sheet-like members 9, the core member being cut at two locations near a mounting portion 10 for mounting the original pressing plate to a copying apparatus body 5, the upper and lower sheet members being joined together at said locations to form hinges B and C. Accordingly, this original pressing plate can press even a thick original 7 as shown in FIG. 2, but the joined hinge portions B and C are liable to peel off and further, this original pressing plate does not have the holding functions in a predetermined degree of opening during opening-closing of the original pressing plate 1' and therefore, the operator must always hold down the original pressing plate 1' or a support 11 must be secured to the mounting portion 10 side and thus, this original pressing plate has required a number of parts which in turn has led to problems of manufacturing cost and operability.